I'm not really good at inserting images :-) but I will try to guide you:
contact ("Nous contacter"), the following scren should give you "Contacts in France" followed by "Other contacts". If you click on "Contacts in France", it gives you "Your dedicated line, accessible 24/7" and if you click on that your phone should compose the number, which starts as +33 1 49... and connect you directly to the Plat line where they should already know who's the caller. I have an iPhone, not sure if on other phones is different. Hope this helps.